I've made the site you are looking at right now in just three weeks. It has 1.5k+ users and more than 50 paid customers (in four days since opening the BETA). People asked me how I was able to build this (plus the iOS app) so quickly.
I've programmed in almost all languages, in small projects and big 300+ Million users (Twitter, LinkedIn, etc.), and I've always found myself coming back to Ruby on Rails. I'm convinced I would have never been able to create this site in just three weeks using any other language.
Convention over configuration, simple abstractions, and so much more with the small tradeoff of runtime speed. I love the JVM, it's a remarkable tool, new languages like Kotlin are fantastic, even Java is usable now, but the sheer speed of iteration and flexibility that Rails has to offer still blows my mind.
require 'rails/all' # 💛